Background: The first two years of life are a critical window for ensuring optimal child growth and development. Nutritional deficiencies during this period can lead to impaired cognitive development, compromised educational achievement and low economic productivity which become difficult to reverse later in life. Improving infant and young child feeding (IYCF) practices is critical for improved nutrition, health and development. So, this study was aimed to assess practices of appropriate complementary feeding and associated factors among mothers of children aged 6 - 23 months. Objectives: To assess the prevalence of appropriate complementary feeding practices and associated factors among mothers of children age 6 - 23 months in Arada sub city of Addis Ababa city administration. Methods: Facility based Cross-sectional study was conducted in Arada sub city selected health facilities among randomly selected 300 mothers who have children age 6-23 months. Data were collected using pre-tested structured questionnaire. Data were entered in to Epi info and exported to SPSS version 20 for cleaning and analysis. Descriptive data were generated by using frequency table to assess prevalence and Socio demographic characteristics. Adjusted odds ratio at 95% confidence interval was computed to measure the strength of association and P- value <0.05 was reported as considering significant association. Result: The overall prevalence of appropriate complimentary feeding practice was 9.5% with aggregation of timely initiation of complementary feeding; minimum frequency of feeding; minimum dietary diversity and minimum acceptable diet which were 63.2%, 22.4%, 21.6% and 16.7% among mothers of 6 - 23 months aged children, respectively. Age of mothers; mother’s educational status, mother’s occupation and counseling of mothers during postnatal care services were significantly associated factors with appropriate complimentary feeding practice at P Value <0.05. Conclusion: Appropriate complementary feeding of children aged 6-23 months was very low in this study. Mothers who are employed, younger age and advised during post natal care were associated factors with appropriate feeding practices. So, educating mothers and expanding nutrition related education is recommended.